Neurocognitive impairment in bipolar disorder patients: functional implications

Abstract

Growing evidence suggests that bipolar disorder (BPD) patients experience prominent neurocognitive impairment not only during acute mood episodes (1-3) but also during euthymia (1,(4)(5)(6)(7)(8)(9)(10)(11)(12). A recent meta-analytic review of 39 studies comparing neurocognitive functioning in 948 euthymic BPD patients and 1,128 normal controls, matched for age, sex, education, and estimated premorbid IQ, found medium-to-large effect sizes (ES, as group differences ⁄ variance) for impaired attention and processing speed (ES = 0.60-0.79), episodic memory (ES = 0.43-0.81), and executive functioning (ES = 0.47-0.71) in the BPD patients (11). Another meta-analytic review of 20 studies, also comparing neurocognitive performance in euthymic BPD patients to matched normal controls, found deficits of similar magnitude in measures of executive functions, verbal learning, immediate Background: Functional recovery among treated bipolar disorder (BPD) patients is far less likely than syndromal and even symptomatic recovery. We hypothesized that increasingly well-documented aspects of cognitive impairment may contribute to poor functional outcomes in BPD patients, and reviewed the available research on the topic.Methods: Computerized literature searching identified 12 studies with 13 comparisons that simultaneously evaluated cognitive and functional status in euthymic (n = 8) or non-euthymic (n = 5 comparisons) adult BPD patients versus otherwise similar healthy controls.Results: In 6 ⁄ 8 studies of euthymic BPD patients and 5 ⁄ 5 studies of non-euthymic BPD patients, neurocognitive impairment was significantly associated with impaired psychosocial functioning, even after adjusting for residual mood symptoms and relevant demographic and clinical variables. Cognitive status was consistently assessed with standardized, performance-based neuropsychological tests, but functional status usually was based on subjective self-appraisals. Approximately 55% of BPD patients were unemployed.Conclusions: Available studies are limited by subjective assessments of functional status rather than objective, performance-based measures. Nevertheless, they support the hypothesis that enduring aspects of cognitive impairment found even in euthymic BPD patients are associated with inferior functioning. These findings encourage further studies with better assessment methods and greater rehabilitative efforts in BPD patients.

Cognitive Impairment in Bipolar Disorder

“…A review of 13 studies involving a total of 813 bipolar patients found an unemployment rate of 55% (ref. 42 ). Functional outcomes in bipolar disorder are affected by various factors such as neuroticism and current level of depressive symptoms 43 as well as age, course of disorder (single episode, multiple episodes, chronic deteriorating course) insight into positive symptoms, family history of schizophrenia, and lifetime substance use disorders 44 ; other clinical and demographic factors have been described 41 .…”

Clinical implications of cognitive function in bipolar disorder

“…Persistent depressive symptoms emerged as the most important predictor of poor outcome but 40% of the variance remained unaccounted for suggesting that explanatory models of the functional outcome in BD that are focused on clinical variables only do not capture the full range of possible predictors. These findings have shifted research interest towards cognitive dysfunction as the potential 'missing link' mediating psychosocial disability in BD (reviewed by Wingo et al [2009a]). …”

Bipolar disorder – diagnosis and current treatment options

“…3 The disorder is a significant cause of disability and suffering. 4,5 A recent international study reported that the median age at onset is 24 years for men and 27 years for women with a range of 10 to 42 years, 6 although most individuals with bipolar disorder report problems with mood and anxiety symptoms in adolescence and early adulthood.…”